The RV790 is not just an overclocked RV770. DailyTech noticed the RV790 chip was slightly larger than the RV770 when we acquired a reference board several weeks ago. It is a new respin of the original silicon, with retrained and rearchitectured power paths for greater power efficiency. ATI engineers also used decoupling capacitors in a decap ring to increase signal integrity.

All of this enables higher clock speeds. While the Radeon 4870 has a core clock of 750MHz, the Radeon 4890 runs its core clock at 850MHz. The standard GDDR5 runs at 3.9GHz effective, and provides 124.8 GB/s of bandwidth. Several ATI graphics board partners will be launching models with core clocks running at over 1GHz using improved cooling solutions.

Power consumption is also greatly reduced. The Radeon 4890 board consumes approximately 60W at near idle loads, such as when displaying 2D graphics or working on Word or Excel documents. This cuts powers consumption by a third from the Radeon 4870, which utilizes 90W at idle.

On the flip side, maximum board power is now rated at 190W with the 4890, an increase of 30W. This is due to the higher clock speeds of both the GPU and the GDDR5 memory.

DailyTech has performed a few basic tests of the Radeon 4890, and our results show a 10%-25% performance improvement, depending on the game. The drivers in the box will work best for now, until the Catalyst 9.4 drivers are released later this month.

We have received word that there are over 50,000 Radeon HD 4890 cards already in the market. Several retailers have already sold cards to anxious fans ahead of today's launch date. The cards themselves should sell for no more than $250 at stock speeds, although we expect prices to drop slightly in a month's time. Some partners have also said that mail-in rebates for $20 will be available.

AMD recently tried to lower prices on its Radeon 4870 and 4850 cards, but its board partners believe that the performance of the Radeon 4870 is too good to lower prices further. The 1GB version of the Radeon 4870 is now selling for around the $180 mark, although it may be available for less with a mail-in rebate partly subsidized by AMD.

The primary competition for the Radeon HD 4890 will be NVIDIA's GeForce GTX 275, which is also priced at around $250. However, there will be no retail availability until April 14th, when it was originally supposed to be launched. Even so, our sources say that NVIDIA will not have the volumes that it needs to meet demand, which may end up raising prices.

Further out, ATI will be launching its first DirectX 11 parts in late summer. Some consumers may be tempted to wait for the next generation of cards with an all new architecture, but they will launch at higher prices. If you're looking for a high performance single chip video card, the Radeon 4890 may be your best bet for the next five months.

UPDATE: ATI has confirmed that the original information we received was incorrect, and the RV790 does indeed have 959 million transistors.